微小シャルピー衝撃試験片によるCr-Mo-V鋳鋼の経年劣化評価

概要

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There are two methods of evaluation of material degradation, that is, destructive and non-destructive. In this study, the degradation of Cr-Mo-V casting steel which has been used for about ten years as the internal casing of turbine was evaluated using a miniature Charpy impact specimen. The miniature specimen (thickness : 1.5 mm, width : 1.5 mm, length : 16 mm) was taken from the Cr-Mo-V casting steel and the ductile-brittle transition curve was measured by the instrumented Charpy impact test. Moreover, the effects of specimen dimension on the ductile-brittle transition temperature (DBTT) and upper shelf energy and a relationship between the change of DBTT and micro -structural properties were investigated. The results of this study are summarized as follows : (1) When the specimen dimension becomes smaller, the difference of DBTT due to the difference in degradation becomes smaller. (2) The degradation of material can be successfully evaluated with a 1/6 size specimen. (3) The change of DBTT can be predicted from the changes of hardness, innergranular hardness, diameter of precipitated carbide and depth of etched grain boundary groove.
社団法人日本材料学会の論文
1992-08-15